How hormonal factors affect breast cancer risk?
Some hormonal factors have been suggested as breast cancer risk factors. In particular, it is known that early menarche (first period) and late menopause increase the risk of breast cancer. Breast-feeding lowers the risk of breast cancer, as does early childbirth (before the age of 30). It is known that the pill lowers the risk of ovarian cancer when taken for 5 or more years. However, there may be a slightly increased chance of developing breast cancer for women who take the pill for prolonged periods, although this risk decreases once women stop taking the pill. Hormone replacement therapy (HRT) increases the risk of breast cancer when used after a natural menopause. However, it may be helpful for women who have an early surgically induced menopause.